The present invention relates to sliding doors for a vehicle, more particularly to lightweight aluminum thin sliding doors for vehicles.
Sliding doors are frequently installed in several types of vehicles including passenger vans and, more prominently, minivans. In minivans, the right side passenger door or the right side passenger door and the left side passenger door are slidable in tracks formed in the body of the vehicle. These doors provide access to the passenger compartment of the vehicle via a relatively wide opening.
Sliding doors should seal off the environment such as water, air, and noise. Accordingly, the door structure must be rather rigid and also must meet the safety limitations of the Federal Motor Vehicle Safety Standard (FMVSS214) which requires that the door provide a specified degree of protection from intrusion into the passenger compartment for occupants of the vehicle upon side impact. In order to achieve the strength and stiffness needs for the door and to meet the minimum safety requirements, the doors are typically fashioned from thick and strong components formed from steel. These currently available steel sliding doors are heavy, over about 44 pounds for a DiW (door in white), and relatively thick, typically about 120 mm in cross-section. Lighter weight metals such as aluminum are generally unsuitable for use at this thickness due to manufacturing difficulties. If a steel door were made thinner to reduce its weight, the resulting structural performance would be unacceptable.
An additional drawback to conventional heavy sliding doors is that they are difficult to open and close, especially when the vehicle is parked on a hill, and need a correspondingly heavier mechanism to retain the door in an open position. For smaller individuals, including children, conventional sliding doors are prohibitively difficult to open and close. Some sliding doors are equipped with motors for power operation of the door. Power driven sliding doors overcome some of the difficulties experienced by certain individuals in opening and closing the doors, however the weight of the doors remains problematic for both the power requirement for the door motors and for the overall vehicle weight.
Conventional steel doors are typically manufactured from an inner panel and an outer panel of steel. The steel panels provide both structural strength for the door and act as panels for mounting of door hardware as well as serve an ornamental function. The peripheries of each of the inner and outer panels include a U-shaped embossment above the beltline of the door. These embossments are aligned with the openings of the U-shapes facing each other to form a box beam at the periphery of the assembled door. The inner panel and the outer panel are joined together below the beltline along their peripheries with a gap maintained between the inner and outer panels in the central portion of the door. A plurality of tabs integrally formed with the inner panel are bent in a direction away from the inner panel. The ends of the tabs abut the inside surface of the outer panel thereby creating stiffening bridges between the inner panel and the outer panel. The gap between the inner and outer panels is sized to allow for insertion and future maintenance of the door handle and lock hardware between the inner and outer panels of the door and also to provide adequate structural stiffness of the door. Hence, the cross-sectional thickness of a conventional steel door is typically over 120 mm which constrains the use of lighter materials such as aluminum. A further difficulty associated with conventional doors is that the available interior space of the vehicle is diminished by the thickness of the doors.
Numerous components such as the hardware for the door handle and the door lock and stereo speakers are inserted in the gap between the inner and outer panels through cutouts in the inner panel of the door. Hence, the gap between the inner and outer panels must be sufficiently large to accommodate the door hardware and other vehicle accouterments. Installation and maintenance of these components is cumbersome and requires specialized techniques and tools for accessing the gap between the inner and outer panels.
In an attempt to reduce the weight of vehicle body panels, certain body panels have been made from lightweight materials such as aluminum and plastic. For example, U.S. Pat. No. 5,449,213 discloses an aluminum movable liftgate having a tubular frame sandwiched between a pair of inner panels and a pair of outer panels. The frame functions as the load bearing structure for the liftgate, however, there is no provision in the disclosed panel for the hardware or for the contour and other design requirements of a sliding door installed on the side of a vehicle.
Accordingly, a need remains for a thin, light-weight sliding door which maximizes the vehicle interior space and which also allows ready access to the door hardware.
This need is met by the vehicle sliding door of the present invention. The present invention includes a vehicle door having an inner panel and an outer panel and a space frame. The inner panel, the outer panel and the space frame may be made from a variety of materials including aluminum, steel and plastic, with aluminum being preferred. The inner panel defines a window opening and an outside surface of the inner panel defines a U-shaped channel surrounding a portion of the window opening. The space frame, which primarily carries the structural load in the door, is positioned in the U-shaped channel and includes a hydroformed aluminum tube with a longitudinally extending flange which is fixed to the inner panel. The tube has a U-shaped configuration and extends across the top portion of the inner panel and includes one leg extending to a lower portion of one end of the inner panel and another leg extending to a lower portion of the other end of the inner panel. The space frame further includes an anti-intrusion beam fixed at each end thereof to one of the legs of the tube. The anti-intrusion beam defines a xcexa3-shaped channel and includes filler material (e.g., foam) positioned within the channel. The inner panel defines an opening which receives a window. The outer panel is fixed to the outside surface of the inner panel at a position below the window opening and an outer valence is mounted on the outside surface of the inner panel at a position above the window opening.
The inner panel inside surface includes one or more depressions with corresponding raised portions, preferably frustoconically shaped, on the inner panel outer surface which are maintained spaced apart from the outer panel via cushioning members. The depressions may be configured to provide packaging clearance for a power door drive motor, door latch mechanisms and the like. A housing/carrier is fastened to the inside surface of the inner panel and is configured to receive door hardware such as lock mechanisms. The door further includes at least one bracket mounted to the inner panel inside surface and fixed to the space frame for mounting the door in a vehicle body. The overall cross-sectional thickness of the door is about 35 mm or less.
The present invention further includes a method for manufacturing a vehicle door having the steps of stamping an inner door panel with a window opening and an outer door panel from a sheet of material and assembling a space frame between the inner panel and the outer panel. The step of stamping the inner panel includes forming (i) depressions on the inside surface thereof with corresponding raised portions on the inner panel outside surface and (ii) a U-shaped channel surrounding the window opening. During the stamping process, material from the sheet used to produce the window opening in the inner panel may be used to produce a housing for a door lock hardware carrier. The space frame is preferably formed by bending the tube into a U-shape having a top portion and a pair of legs extending from the top portion and mounting a beam at each end thereof to the legs and then hydroforming the tube with an integrally formed longitudinally extending flange. In assembling the door, the tube is flush assembled to the anti-intrusion beam and then seated within the U-shaped channel and the flange of the tube is fixed to the inner panel. The method further includes stamping a valence from a sheet of material and fixing the valence to the inner panel at a position above the window opening. Preferably, the valence and the outer panel are stamped adjacent each other from a single sheet of material.